test: drop gratuitous --subnet args; add focused subnet-routing tests

crates/icp-cli/tests/canister_create_tests.rs

@@ -73,6 +73,68 @@ async fn canister_create() {
     );
 }
 
+/// Verifies that `canister create --subnet <id>` creates the canister on the requested subnet.
+///
+/// The network is configured with multiple application subnets so the placement is an actual
+/// choice: if `--subnet` were ignored (and a subnet picked by default instead), the canister
+/// could land on a different one and the assertion would fail.
+#[tokio::test]
+async fn canister_create_on_requested_subnet() {
+    let ctx = TestContext::new();
+    let project_dir = ctx.create_project_dir("icp");
+
+    let pm = formatdoc! {r#"
+        canisters:
+          - name: my-canister
+            build:
+              steps:
+                - type: script
+                  command: echo hi
+
+        networks:
+          - name: random-network
+            mode: managed
+            gateway:
+              port: 0
+            subnets: [application, application]
+        {ENVIRONMENT_RANDOM_PORT}
+    "#};
+
+    write_string(&project_dir.join("icp.yaml"), &pm).expect("failed to write project manifest");
+
+    let _g = ctx.start_network_in(&project_dir, "random-network").await;
+    ctx.ping_until_healthy(&project_dir, "random-network");
+
+    let subnet_id = ctx.application_subnet_id().await;
+
+    let icp_client = clients::icp(&ctx, &project_dir, Some("random-environment".to_string()));
+    icp_client.mint_cycles(10 * TRILLION);
+
+    ctx.icp()
+        .current_dir(&project_dir)
+        .args([
+            "canister",
+            "create",
+            "my-canister",
+            "--subnet",
+            &subnet_id,
+            "--environment",
+            "random-environment",
+        ])
+        .assert()
+        .success();
+
+    // The canister must be created on exactly the subnet we requested.
+    let actual_subnet = clients::registry(&ctx)
+        .get_subnet_for_canister(icp_client.get_canister_id("my-canister"))
+        .await;
+    assert_eq!(
+        actual_subnet.to_string(),
+        subnet_id,
+        "canister should be created on the requested subnet"
+    );
+}
+
 #[tokio::test]
 async fn canister_create_with_settings() {
     let ctx = TestContext::new();
@@ -979,23 +1041,7 @@ async fn canister_create_cloud_engine() {
 
     // Find the CloudEngine subnet by querying the topology endpoint
     // TODO replace with a subnet selection parameter once we have one
-    let topology_url = ctx.gateway_url().join("/_/topology").unwrap();
-    let topology: serde_json::Value = reqwest::get(topology_url)
-        .await
-        .expect("failed to fetch topology")
-        .json()
-        .await
-        .expect("failed to parse topology");
-
-    let subnet_configs = topology["subnet_configs"]
-        .as_object()
-        .expect("subnet_configs should be an object");
-    let cloud_engine_subnet_id = subnet_configs
-        .iter()
-        .find_map(|(id, config)| {
-            (config["subnet_kind"].as_str()? == "CloudEngine").then_some(id.clone())
-        })
-        .expect("no CloudEngine subnet found in topology");
+    let cloud_engine_subnet_id = ctx.cloud_engine_subnet_id().await;
 
     // Create the canister on the CloudEngine subnet
     // Only the admin can do this. In local envs, the admin is the anonymous principal

crates/icp-cli/tests/canister_delete_tests.rs

@@ -45,13 +45,7 @@ async fn canister_delete() {
 
     ctx.icp()
         .current_dir(&project_dir)
-        .args([
-            "deploy",
-            "--subnet",
-            common::SUBNET_ID,
-            "--environment",
-            "random-environment",
-        ])
+        .args(["deploy", "--environment", "random-environment"])
         .assert()
         .success();
 

crates/icp-cli/tests/canister_info_tests.rs

@@ -45,13 +45,7 @@ async fn canister_status() {
 
     ctx.icp()
         .current_dir(&project_dir)
-        .args([
-            "deploy",
-            "--subnet",
-            common::SUBNET_ID,
-            "--environment",
-            "random-environment",
-        ])
+        .args(["deploy", "--environment", "random-environment"])
         .assert()
         .success();
 

crates/icp-cli/tests/canister_metadata_tests.rs

@@ -45,13 +45,7 @@ async fn canister_metadata() {
 
     ctx.icp()
         .current_dir(&project_dir)
-        .args([
-            "deploy",
-            "--subnet",
-            common::SUBNET_ID,
-            "--environment",
-            "random-environment",
-        ])
+        .args(["deploy", "--environment", "random-environment"])
         .assert()
         .success();
 
@@ -109,13 +103,7 @@ async fn canister_metadata_not_found() {
 
     ctx.icp()
         .current_dir(&project_dir)
-        .args([
-            "deploy",
-            "--subnet",
-            common::SUBNET_ID,
-            "--environment",
-            "random-environment",
-        ])
+        .args(["deploy", "--environment", "random-environment"])
         .assert()
         .success();
 

crates/icp-cli/tests/canister_settings_tests.rs

@@ -55,13 +55,7 @@ async fn canister_settings_update_controllers() {
 
     ctx.icp()
         .current_dir(&project_dir)
-        .args([
-            "deploy",
-            "--subnet",
-            common::SUBNET_ID,
-            "--environment",
-            "random-environment",
-        ])
+        .args(["deploy", "--environment", "random-environment"])
         .assert()
         .success();
 
@@ -425,13 +419,7 @@ async fn canister_settings_update_log_visibility() {
 
     ctx.icp()
         .current_dir(&project_dir)
-        .args([
-            "deploy",
-            "--subnet",
-            common::SUBNET_ID,
-            "--environment",
-            "random-environment",
-        ])
+        .args(["deploy", "--environment", "random-environment"])
         .assert()
         .success();
 
@@ -731,8 +719,6 @@ async fn canister_settings_update_miscellaneous() {
         .current_dir(&project_dir)
         .args([
             "deploy",
-            "--subnet",
-            common::SUBNET_ID,
             "--cycles",
             "120t", // 120T cycles because compute allocation is expensive
             "--environment",
@@ -859,13 +845,7 @@ async fn canister_settings_update_environment_variables() {
 
     ctx.icp()
         .current_dir(&project_dir)
-        .args([
-            "deploy",
-            "--subnet",
-            common::SUBNET_ID,
-            "--environment",
-            "random-environment",
-        ])
+        .args(["deploy", "--environment", "random-environment"])
         .assert()
         .success();
 
@@ -1036,13 +1016,7 @@ async fn canister_settings_sync() {
 
     ctx.icp()
         .current_dir(&project_dir)
-        .args([
-            "deploy",
-            "--subnet",
-            common::SUBNET_ID,
-            "--environment",
-            "random-environment",
-        ])
+        .args(["deploy", "--environment", "random-environment"])
         .assert()
         .success();
 
@@ -1220,13 +1194,7 @@ async fn canister_settings_sync_log_visibility() {
 
     ctx.icp()
         .current_dir(&project_dir)
-        .args([
-            "deploy",
-            "--subnet",
-            common::SUBNET_ID,
-            "--environment",
-            "random-environment",
-        ])
+        .args(["deploy", "--environment", "random-environment"])
         .assert()
         .success();
 
@@ -1458,13 +1426,7 @@ async fn canister_settings_show() {
 
     ctx.icp()
         .current_dir(&project_dir)
-        .args([
-            "deploy",
-            "--subnet",
-            common::SUBNET_ID,
-            "--environment",
-            "random-environment",
-        ])
+        .args(["deploy", "--environment", "random-environment"])
         .assert()
         .success();
 
@@ -1555,13 +1517,7 @@ async fn canister_settings_show_not_a_controller() {
 
     ctx.icp()
         .current_dir(&project_dir)
-        .args([
-            "deploy",
-            "--subnet",
-            common::SUBNET_ID,
-            "--environment",
-            "random-environment",
-        ])
+        .args(["deploy", "--environment", "random-environment"])
         .assert()
         .success();
 

crates/icp-cli/tests/canister_start_tests.rs

@@ -48,13 +48,7 @@ async fn canister_start() {
 
     ctx.icp()
         .current_dir(&project_dir)
-        .args([
-            "deploy",
-            "--subnet",
-            common::SUBNET_ID,
-            "--environment",
-            "random-environment",
-        ])
+        .args(["deploy", "--environment", "random-environment"])
         .assert()
         .success();
 

crates/icp-cli/tests/canister_status_tests.rs

@@ -48,13 +48,7 @@ async fn canister_status() {
 
     ctx.icp()
         .current_dir(&project_dir)
-        .args([
-            "deploy",
-            "--subnet",
-            common::SUBNET_ID,
-            "--environment",
-            "random-environment",
-        ])
+        .args(["deploy", "--environment", "random-environment"])
         .assert()
         .success();
 

crates/icp-cli/tests/canister_stop_tests.rs

@@ -47,13 +47,7 @@ async fn canister_stop() {
         .mint_cycles(10 * TRILLION);
     ctx.icp()
         .current_dir(&project_dir)
-        .args([
-            "deploy",
-            "--subnet",
-            common::SUBNET_ID,
-            "--environment",
-            "random-environment",
-        ])
+        .args(["deploy", "--environment", "random-environment"])
         .assert()
         .success();
 

crates/icp-cli/tests/common/context.rs

@@ -355,6 +355,48 @@ impl TestContext {
         self.http_gateway_url.get().unwrap()
     }
 
+    /// Returns the ID of an application subnet of the running network.
+    ///
+    /// See [`subnet_id_by_kind`](Self::subnet_id_by_kind) for why discovery happens at runtime.
+    pub(crate) async fn application_subnet_id(&self) -> String {
+        self.subnet_id_by_kind("Application").await
+    }
+
+    /// Returns the ID of a CloudEngine subnet of the running network.
+    ///
+    /// See [`subnet_id_by_kind`](Self::subnet_id_by_kind) for why discovery happens at runtime.
+    pub(crate) async fn cloud_engine_subnet_id(&self) -> String {
+        self.subnet_id_by_kind("CloudEngine").await
+    }
+
+    /// Returns the ID of a subnet with the given `subnet_kind`, querying the running network's
+    /// `/_/topology` endpoint. A topology may contain more than one subnet of a kind; this
+    /// returns one of them and panics if none exist.
+    ///
+    /// Subnet IDs are derived deterministically from the launcher topology, so adding or
+    /// removing subnets shifts them. Discovering the ID at runtime keeps the tests robust
+    /// against launcher topology changes instead of hard-coding an ID.
+    ///
+    /// The network must be started and healthy before calling this.
+    async fn subnet_id_by_kind(&self, subnet_kind: &str) -> String {
+        let topology_url = self.gateway_url().join("/_/topology").unwrap();
+        let topology: serde_json::Value = reqwest::get(topology_url)
+            .await
+            .expect("failed to fetch topology")
+            .json()
+            .await
+            .expect("failed to parse topology");
+
+        topology["subnet_configs"]
+            .as_object()
+            .expect("subnet_configs should be an object")
+            .iter()
+            .find_map(|(id, config)| {
+                (config["subnet_kind"].as_str()? == subnet_kind).then_some(id.clone())
+            })
+            .unwrap_or_else(|| panic!("no {subnet_kind} subnet found in topology"))
+    }
+
     pub(crate) fn agent(&self) -> Agent {
         let agent = Agent::builder()
             .with_url(self.http_gateway_url.get().unwrap().as_str())

crates/icp-cli/tests/common/mod.rs

@@ -40,14 +40,6 @@ environments:
     network: docker-engine-network
 "#;
 
-/// This ID is dependent on the toplogy being served by pocket-ic
-/// NOTE: If the topology is changed (another subnet is added, etc) the ID may change.
-/// References:
-/// - http://localhost:8000/_/topology
-/// - http://localhost:8000/_/dashboard
-pub(crate) const SUBNET_ID: &str =
-    "cok7q-nnbiu-4xwf6-7gpqg-kwzft-mqypn-uepxh-mx2hy-q4wuy-5s5my-eae";
-
 // Spawns a test server that expects a single request and responds with a 200 status code and the given body
 pub(crate) fn spawn_test_server(method: &str, path: &str, body: &[u8]) -> httptest::Server {
     // Run the server